Method of increasing cargo-carrying capacity of vessels.



F. L. SAWYER.

METHOD OF INCREASING CARGO CARRYING CAPACITY OF VESSELS.

APPLICATION FILED MAR- 9. I916.

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rm: COLUMBIA PLANDGRAPH co., WASHINGTON, n. c.

FREDERICK LEWIS SAWYER, OF NEW YORK. N. Y;

METHOD OF INCREASING CARGO-CARRSTING CAPACITY OF VESSELS.

IJSQLIEMC.

Application filed March 9, 1916.

To all whom it may concern: I 7

Be it known that I, FREDERICK Lnwrs SAwYnn, a citizen of the UnitedStates, residing at New York, in the county of New York and State of NewYork, have invented certain new and useful Improvements in Methods ofIncreasing Cargo-Carrying Capacities of Vessels; and I do hereby declarethe following to be a full, clear, and exact description of theinvention, such as wlll enable others skilled in the art to which itappertains to make and use the same.

My invention relates to the method of preventing the increase of draftof vessels, due to inequalities between the temperature of the parts ofthe vessel below the water line, and those parts of the vessel above thewater line.

The vessel may be considered as a hollow longitudinal box girder,comprising, mainly, the skin plating, the decks, the frames, and otherparts connecting the two. Part of the ship when afloat is submergedbelow the water line, and part is above the water line. In certain timesof the year, and in certain localities, the water is very much colderthan the air, and again under other conditions the air is very muchcolder than the water. When the water is colder than the air, there is atendency of the submerged parts of the girder to contract, and the partsof the vessel not submerged to expand, causing a depression of the twoends of the girder, or, as it is technically known, hogging of thevessel. On the contrary, if the air is colder than the water there willbe a tendency of the upper part of the girder to contract, and of thelower part of the vessel to expand, causing a tilting up of the two endsof the vessel, which results in a bending down of the vessel amidships,or increasing the draft amidships, which is technically known assagging. Either of these results tends to increase the draft of thevessel, either forward or aft, or amidships, as the case may be, abovethe normal mean draft of the vessel. Under ordinary harbor conditions,this may not be important, but where the vessel has to go through canalsof a predetermined depth, or cross bars where the water is comparativelyshallow, it is desirable to carry as much cargo as possible, and aslight change of draft may be very material.

The hogging and sagging of vessels, due

Specification of Letters Patent.

Patented Apr. 18, 1916.

Serial No. 83,147.

to temperature, is of more importance in the case of iron or steelvessels, and is particularly important in the case of long and shallowfreighters, such as ore or grain carriers, or colliers, or the like,especially those which are designed to go through canals of limiteddepth. It has been known in practice that long steel vessels in summercruising in cold water increase their normal draft as much as six inchesby the bow and stern, which is entirely due to the upper portion of thevessel being of considerably higher temperature than the submergedportion of the vessel. This tendency to hog is more accentuated than thetendency to sag, be cause of the fact that the ends of the girder at thebow and stern are comparatively sharp, and displace far less water forthe same draft than would result from any sagging effect due to the sameconditions in temperature, where the upper portion of the vessel was atconsiderably lower temperature than the submerged portion of the vessel.This excess due to hogging is further augmented because of the fact thatthe air frequently reaches a temperature far higher than is ever reachedin the water of flotation; and the differences in temperature betweenthe air and the water of flotation are more apt to be greater insummertime than would be the corresponding differences of temperature inthe winter.

According to my invention I purpose to obviate these objections bycausing the exposed and the submerged parts of the vessel to be broughtas nearly as possible to the same temperature, either when loadingalongside dock, or when going through canals, crossing a bar, etc, wherethese conditions in draft might be of material importance. To securethis result I apply the water of flotation to the exposed parts of thevessel as far as practicable, as by pumping same through a plurality ofhose, so that the entire girder may be brought to a substantiallyuniform temperature, and so that any previous hogging or sagging may becompensated for by the contraction or expansion of the upper parts ofthe vessel when so treated with the water of flotation.

Reference is had to the accompanying drawings, in which Figure 1 shows aside elevation of an ordinary ore carrier or collier; and Fig. 2 is adiagram showing'the effect of hogging and sagging on the f keel of thevessel due to corrected and uncorrected temperature changes.

Referring to Fig; 1, A B represents the keel line of the vessel, and inFig. 2 this is shown in full lines when the vessel is loaded on an evenkeel by correcting for any" temperature difierences so that the vesselis neither hogged nor sagged at the time of loading. When the lower partof the vessel is'at a lower temperature-thanrtheparts of. the. hullabove the water line, the keel. line:

would assume the position indicated by the:

dotted lines A B inzFi'g. 2; In. this case the keel would be-hogged upamidshipstas keel line would assume the position indicat ed at A 13showinga sagvamidships, as:

at a and aliftingup of theends as at 6 Thus,, it will be seen thatWhenthe. submerged portion of the ship is colder than the upper portion,therewill be a hogging Copies ot thii patent may be obtained tor fivecents each, by. addressing. the Commissioner ot- Patents,

up of the amidships portion of the'keel, and a sagging down of the bowand stern portions, thus increasing the draft by the bow and stern;while if the upper portion of the ship is colder, there will be asagging down of the amidships portion of the ship and a tilting up ofthe bow and stern; in both cases causing increase of draft which, incertain cases, isvery undesirable, as it reduces the amount of cargothat the vessel can carrying for-a predetermined draft.

Having thus described my invention what I claim and desire to secure byLetters Patent ofthe United States is The method of preventing, increasein draft of a vessel where there is a substan tial difference oftemperature between the air and the water of flotation, which consistsin .applyingthe water of flotation to th upper portions ofvthe vesselfor the purpose of approximately equalizing the temperature of the hullabove the water line with the temperature of the hull below the waterline, thereby preventing or reducing hogging, or sagging.

In. testimony whereof, I aflix my signature.

FREDERICK LEWIS SAWYER.

Washington; D. 0.

